Looking to the west at the Tempiute Mountain thrust sheet, Nevada (background)
from the Monte Mountain thrust sheet in the Pahranagat Range. The faint
road in the upper left corner is the main service road into the secret
Air Force Area 51 at Groom Lake.

NORTH >>>>

NORTH >>>>

Area 51 lies near the epicenter of a Late Devonian cosmolite that created an
impact crater more than 100 miles in diameter. The resulting impact breccia
falling back into the crater is more than 400 feet thick at Tempiute Mountain. It
lies within the Late Cretaceous Cordilleran fold and thrust belt.

Only after thrust restoration does the distribution of facies deposited on the
breccia make depositional sense:

• Deepwater ribbon limestone in the middle of the impact basin,
• Shallow-water intertidal sandstones on the western edge of the basin
  near the Devonian Antler forebulge, and
• Classic Devonian reefs on the more open-marine east side.
• Brown sandstones lie on the gray prominent ledges of impact breccia.
• Deepwater ribbon limestones lie on the breccia in the Tempiute
  Mountain thrust sheet north of Groom Lake.
• Classic Canadian Devonian reefs lie above the breccia in the footwall
  of the Monte Mountain thrust sheet to the east.

Thrust restoration of the impact basin provides a powerful oil and gas
exploration tool that helps to model hydrocarbon-bearing compressional
features in Nevada.

Photos courtesy of Alan Chamberlain, CEDAR STRAT